This disclosure relates to evaporative emissions treatment systems and, more particularly, to a photocatalytic system for evaporative emissions treatment systems.
To reduce hydrocarbon emissions from engine exhaust, engine exhaust treatment devices typically employ catalytically active material comprising precious metals. However, conventional precious metal catalyst materials are essentially inactive at operating temperatures below 140xc2x0 C. However, certain applications, such as an evaporative emissions system for a fuel system are not exposed to operating temperatures as high as 140xc2x0 C. because such operating conditions are not desirable.
To overcome this disadvantage certain applications employ a photocatalytically active material to treat air, and various types of gases and liquids. For example, U.S. patent application Ser. No. 6,153,159 to Engeler et al., and assigned to Volkswagen AG, disclose one method for catalytically treating exhaust gas produced in an automotive application, which involves subjecting exhaust gas to an illuminated semiconductor photocatalyst in the presence of oxygen. Although Engeler et al. employs a semiconductor photocatalyst to catalytically treat exhaust gas, the catalytic converter design also requires heating a plurality of catalyst supporting plates within the converter.
Typically, photocatalytically active materials require less power to operate efficiently and cost-effectively, unless these photocatalytically active materials also require thermally activated materials, which require even more power to operate than photocatalytically active materials alone. The Engeler et al. catalytic converter design employs both photocatalytically active and thermally active catalytically materials to effectively treat exhaust gas in automotive applications. The design requires heating the catalyst supporting plates, in addition to illuminating a semiconductor photocatalyst, to effectively treat exhaust gases, thereby consuming more power than either a conventional photocatalytically based catalytic converter design or thermally based catalytic converter design.
Accordingly, there exists a need for a system and method for effectively and efficiently photocatalytically treating evaporative emissions.
The drawbacks and disadvantages of the prior art are overcome by the photocatalytic device for fuel tank evaporative emissions, method for photocatalytically treating fuel system evaporative emissions, and the fuel tank evaporative emissions management system. The photocatalytic system for fuel tank evaporative emissions comprises a substrate comprising a photocatalyst and disposed within a shell. The shell preferably comprises one or more sections of transparent material capable of being penetrated by an ultra violet light transmission.
The method for photocatalytically treating evaporative emissions comprises introducing a quantity evaporated fuel to a photocatalytic device. The photocatalytic device comprises a substrate that is illuminated to photocatalytically treat the evaporated fuel.
The fuel tank evaporative emissions management system, comprises a fuel tank and a photocatalytic device in fluid communication with the fuel tank. Disposed in illuminative communication with a photocatalyst in the photocatalytic device is an ultraviolet light source. The photocatalytic device comprises substrate with the photocatalyst and a shell disposed about said substrate.